This volume contains the proceedings of ICTAC 2004, the 1st International Colloquium on Theoretical Aspects of Computing, which was held in Guiyang, China on 20 24 September 2004. ICTAC was founded by the International Institute for Software Technology of the United Nations University (UNU-IIST). Its aim is to bring together pr- titioners and researchers from academia, industry, and government to present research results, and exchange experience, ideas, and solutions for their pr- lems in theoretical aspects of computing. The geographic focus of the ICTAC events is on developing countries to help to strengthen them in their research, teaching, and development in computer science and engineering, to encourage research cooperation among developing countries, and to improve the links - tween developing countries and industrial countries. The Program Committee of ICTAC 2004 received 111 submissions from over 30 countries and regions. Each paper was reviewed, mostly by at least three r- ereesworkinginrelevant?elds,butbytwoinafewcases.Borderlinepaperswere further discussed during an online meeting of the Program Committee. Thir- fourpaperswereacceptedbasedonoriginality,technicalsoundness,presentation andrelevancetosoftwareengineeringandformalmethods.Wesincerelythankall the authors who submitted their work for consideration. We thank the Program Committee members and the other referees for their great e?ort and professional workinthereviewingandselectingprocess.Theirnamesarelistedonthefoll- ing pages. In addition to the contributed papers, the proceedings also includes contributions from the invited speakers: Jos e Luiz Fiadeiro, He Jifeng, Huimin Lin and Rustan Leino.

Inhalt
Invited Speakers.- Software Services: Scientific Challenge or Industrial Hype?.- Integrating Variants of DC.- Challenges in Increasing Tool Support for Programming.- A Predicate Spatial Logic and Model Checking for Mobile Processes.- Concurrent and Distributed Systems.- Object Connectivity and Full Abstraction for a Concurrent Calculus of Classes.- Specifying Software Connectors.- Replicative Distribution Rules in P Systems with Active Membranes.- A Generalisation of a Relational Structures Model of Concurrency.- A Logical Characterization of Efficiency Preorders.- Inherent Causal Orderings of Partial Order Scenarios.- Atomic Components.- Towards an Optimization-Based Method for Consolidating Domain Variabilities in Domain-Specific Web Services Composition.- Model Integration and Theory Unification.- A Formal Framework for Ontology Integration Based on a Default Extension to DDL.- A Predicative Semantic Model for Integrating UML Models.- An Automatic Mapping from Statecharts to Verilog.- Reverse Observation Equivalence Between Labelled State Transition Systems.- Program Reasoning and Testing.- Minimal Spanning Set for Coverage Testing of Interactive Systems.- An Approach to Integration Testing Based on Data Flow Specifications.- Combining Algebraic and Model-Based Test Case Generation.- Verifying OWL and ORL Ontologies in PVS.- Verification.- Symbolic and Parametric Model Checking of Discrete-Time Markov Chains.- Verifying Linear Duration Constraints of Timed Automata.- Idempotent Relations in Isabelle/HOL.- Program Verification Using Automatic Generation of Invariants,.- Theories of Programming and Programming Languages.- Random Generators for Dependent Types.- A Proof of Weak Termination Providing the Right Way to Terminate.- Nelson-Oppen, Shostak and the ExtendedCanonizer: A Family Picture with a Newborn.- Real Time Reactive Programming in Lucid Enriched with Contexts.- Revision Programs with Explicit Negation.- Real-Time and Co-design.- An Algebraic Approach for Codesign.- Duration Calculus: A Real-Time Semantic for B.- An Algebra of Petri Nets with Arc-Based Time Restrictions.- A Calculus for Shapes in Time and Space.- A Framework for Specification and Validation of Real-Time Systems Using Circus Actions.- Automata Theory and Logics.- Switched Probabilistic I/O Automata.- Decomposing Controllers into Non-conflicting Distributed Controllers.- Reasoning About CoBüchi Tree Automata.- Foundations for the Run-Time Monitoring of Reactive Systems Fundamentals of the MaC Language.- Tutorials at ICTAC 2004.- A Summary of the Tutorials at ICTAC 2004.